How Corona Treatment Works

A corona treating system is designed to increase the surface energy of plastic films, foils and paper in order to allow improved wettability and adhesion of inks, coatings and adhesives. As a result, the materials treated will demonstrate improved printing quality, faster press speeds and less scrap.

Polymer films and objects have chemically inert and non-porous surfaces with low surface tensions causing them to be non-receptive to bonding with substrates, printing inks, coatings, and adhesives.

A corona treating system consists of two major components: the power supply and the treater station.

The power supply accepts standard 50/60 Hz utility electrical power and converts it into single phase, higher frequency (nominally 10 to 30 kHz) power that is supplied to the treater station.

The treater station applies this power to the surface of the material, through an air gap, via a pair of electrodes at high potential and roll at ground potential which supports the material. Only the side of the material facing the high potential electrode should show an increase in surface tension. (If treatment is applied to the other side of the material it is referred to as backside treatment.)

A corona treating system in its simplest form can be portrayed as a capacitor. Voltage is applied to the top plate which, in the case of a corona treating system, would be the electrode. The dielectric portion of the capacitor would be made up of some type of roll covering, air, and substrate in the corona treater.

The final component, or bottom plate, takes the form of an electrically grounded roll. In the corona treating system, the voltage buildup ionizes the air in the air gap, creating a corona, which will increase the surface tension of the substrate passing over the electrically grounded roll.